Antidiabetic and antidepressant potentials of aqueous extract of Bridelia scleroneura Müll. Arg. root bark in a dexamethasone-induced insulin-resistant rat model

Abstract

Bridelia scleroneura is a plant of the Euphorbiaceae family used in traditional medicine to treat diabetes mellitus and depressive psychoses. According to the literature, no antidiabetic or antidepressant studies have been conducted on B. scleroneura . The objective of this study was to evaluate the antidiabetic and antidepressant potential of aqueous extract of B. scleroneura root bark (AEBS) in insulin-resistant rats. An in vitro antidiabetic study was conducted using α-amylase and α-glucosidase enzyme inhibition tests. For the in vivo study, 35 rats were divided into groups of 5 rats each and treated orally for 14 days with metformin (40 mg/kg), imipramine (10 mg/kg), and AEBS (62.5, 125, and 250 mg/kg). One hour later, dexamethasone (1 mg/kg) was administered subcutaneously to induce insulin resistance. To assess depression, forced swimming and sucrose preference tests were performed on days 1 and 14. Body weight, food and water consumption, glycemia, insulin levels, lipid profile, oxidative status, markers of renal and hepatic function, enzymes of carbohydrate metabolism, as well as glucogen, pro-inflammatory cytokines, and monoamine levels were assessed. AEBS inhibited the activity of α-amylase (IC50 = 79.31 ± 0.57 µg/mL) and α-glucosidase (IC50 = 71.25 ± 0.39 µg/mL). It also significantly decreased food and water consumption and the levels of glucose, insulin, total cholesterol, triglycerides, low-density lipoprotein, reduced glutathione, malondialdehyde, tumor necrosis factor-α, interleukins 1β and 6, total bilirubin, creatinine, and urea. AEBS (125 and 250 mg/kg) decreased the activities of alanine aminotransferase, aspartate aminotransferase, glucose-6-phosphatase, and fructose-1,6-diphosphate dehydrogenase and increased the activities of glucokinase, glucose-6-phosphate, catalase, and superoxide dismutase. AEBS significantly increased body weight and levels of glycogen, total protein, albumin, dopamine, and serotonin. AEBS has inhibitory potential on the activity of α-amylase and α-glucosidase. It has hypoglycaemic, antidyslipidaemic, and antidepressant effects and protects organs against oxidative damage.